Construction of an In Situ-Generated Nanoscale Organic–Inorganic Hybrid System Using Hydrogen Bonding Interaction To Assist Thermal Properties of Resins

With the rapid development of science and technology, high-temperature-resistant resin systems are facing more severe challenges in extreme applications. To further improve the comprehensive thermal properties of phthalonitrile resins, an in situ generation of a high-temperature-resistant phthalonitrile resin achieving an organic-inorganic hybridization network is reported. A 3-aminophenol phthalonitrile containing -NH₂ is used as a material to hybridize with prepared calcium phosphate nano-oligomers (CPOs), and the hybrid precursor is named as CAPN. Notably, the hydrogen bonding plays a crucial role in the hybrid, as nanosize control of CPOs, and in the synthesis of CAPN. The presence of hydrogen bonding interaction is proved by Fourier transform infrared, Raman, ³¹P solid-state nuclear magnetic resonance spectra, isothermal differential scanning calorimetric testing, and calculation of apparent activation energy (E_a). Based on organic-inorganic hybrid cross-linked networks formed by resins during the curing process, 50CAPN (the hybrid containing 50 wt % CPOs) has superior thermo-mechanical properties [glass transition temperature (T_g) > 580 °C] and thermal stability [5% pyrolysis temperature (T_d5%(N₂) = 574 °C, T_d5%(air) = 543 °C)] than the blending system 50HAPN [the mixture with 50 wt % nanohydroxyapatite (HAP)]. Additionally, under extreme high temperature and combustion conditions, it demonstrates that 50CAPN has more stable thermo-oxidative aging resistance and flame retardancy than 50HAPN. We believe that this organic-inorganic hybrid system of phthalonitrile formed based on hydrogen bonding will elevate the introduction of the inorganic phase into the organic phase for the preparation of high-temperature-resistant resin systems to a certain level.